ADVANCED SPOT WELDING TECHNOLOGIES OF THIN-WALLED PARTS

At the present stage, resistance spot welding is widely used in the field of mechanical engineering. Positive advantages of this welding process are the considerable level of welding mechanization and automation, versatility and flexibility of the process, relatively small residual deformations. However, the level of defective spot-welds in the mass production of welded structures reaches 5%. Currently, the quality of spot-welded joints is accompanied by increased reliability and durability requirements for welds, a minimum level of residual deformation and minimizing defects as lack of fusion and metal splashing. As a result, modern technologies of double-sided spot welding and general technique of spot-welded joints are considered.Key words: structural diagram, part, electrode, current, spot-weld, cycle, compression bushing.доктор технічних наук Барановський В. М., кандидат технічних наук Лазарюк В. В., Береженко Б. М., Сенчишин В. С. Удосконалений спосіб контактного зварювання тонкостінних виробів / Тернопільський національний технічний університет імені Івана Пулюя, Україна, ТернопільНа сучасному етапі контактне точкове зварювання широко застосовується в галузі машинобудування за рядом позитивних критеріїв – наявності доволі значного рівня механізації та автоматизації зварювальних робіт, універсальності та гнучкості технологічного процесу, відносно незначних залишкових деформації тощо. Незважаючи на це рівень дефектності зварних точок в серійному виробництві зварних конструкцій при виготовленні відповідальних зварних виробів досягає 5%. Тому до якості зварних точкових з’єднань висуваються підвищені особливі вимоги – надійності та стабільної міцності зварних швів, мінімального рівня залишкових деформацій та мінімізованої кількості різних видів дефектів, наприклад, як непроварів і бризів металу у зоні ядра зварювання. На основі проведеного аналізу розглянуто сучасні технології двостороннього контактного точкового зварювання та загальну схему формування точкових зварних з’єднань. Ключові слова: структурна схема, деталь, електрод, струм, зварна точка, цикл, обтискна втулка

Research of the strength of cellular beams with a single and double row arrangement of openings

Cellular beams with circular openings were modeled using the finite element method. The distribution of stresses in the perforation zones of the beam with round openings for the single-row and double-row variants was obtained. A comparative analysis of these beams was carried out for perforated beams of almost the same weight. Recommendations for increasing the durability of beams with perforations of various configurations are provide

Spectral modeling of scintillator for the NEMO-3 and SuperNEMO detectors

We have constructed a GEANT4-based detailed software model of photon transport in plastic scintillator blocks and have used it to study the NEMO-3 and SuperNEMO calorimeters employed in experiments designed to search for neutrinoless double beta decay. We compare our simulations to measurements using conversion electrons from a calibration source of $\rm ^{207}Bi$ and show that the agreement is improved if wavelength-dependent properties of the calorimeter are taken into account. In this article, we briefly describe our modeling approach and results of our studies.Comment: 16 pages, 10 figure

Design, Performance, and Calibration of CMS Hadron-Barrel Calorimeter Wedges

Extensive measurements have been made with pions, electrons and muons on four production wedges of the Compact Muon Solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. Data were taken both with and without a prototype electromagnetic lead tungstate crystal calorimeter (EB) in front of the hadron calorimeter. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. These measurements set the absolute calibration of the HB prior to first pp collisions to approximately 4%

Energy Response and Longitudinal Shower Profiles Measured in CMS HCAL and Comparison With Geant4

The response of the CMS combined electromagnetic and hadron calorimeter to beams of pions with momenta in the range 5-300 GeV/c has been measured in the H2 test beam at CERN. The raw response with the electromagnetic compartment calibrated to electrons and the hadron compartment calibrated to 300 GeV pions may be represented by sigma = (1.2) sqrt{E} oplus (0.095) E. The fraction of energy visible in the calorimeter ranges from 0.72 at 5 GeV to 0.95 at 300 GeV, indicating a substantial nonlinearity. The intrinsic electron to hadron ratios are fit as a function of energy and found to be in the range 1.3-2.7 for the electromagnetic compartment and 1.4-1.8 for the hadronic compartment. The fits are used to correct the non-linearity of the e pi response to 5% over the entire measured range resulting in a substantially improved resolution at low energy. Longitudinal shower profile have been measured in detail and compared to Geant4 models, LHEP-3.7 and QGSP-2.8. At energies below 30 GeV, the data, LHEP and QGSP are in agreement. Above 30 GeV, LHEP gives a more accurate simulation of the longitudinal shower profile

Design, Performance, and Calibration of the CMS Hadron-Outer Calorimeter

The CMS hadron calorimeter is a sampling calorimeter with brass absorber and plastic scintillator tiles with wavelength shifting fibres for carrying the light to the readout device. The barrel hadron calorimeter is complemented with an outer calorimeter to ensure high energy shower containment in the calorimeter. Fabrication, testing and calibration of the outer hadron calorimeter are carried out keeping in mind its importance in the energy measurement of jets in view of linearity and resolution. It will provide a net improvement in missing \et measurements at LHC energies. The outer hadron calorimeter will also be used for the muon trigger in coincidence with other muon chambers in CMS